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Has anyone configured SRST to work with CUCILYNC?  I have set up a 2911 ISR using IOS 15.2(1)T1.  I'm using CUCM 8.6(2).  I have set up SRST in CUCM and in the IOS such that hard phones will register with the voice gateway.  But when a CUCILYNC device tries to register the message that it displays in the Notifications window is that it is unable to connect and it's waiting to try again.  I'm assuming there's some other configuration somewhere that I'm missing, but I haven't been able to find any other information.

New Member


I messed with this long enough that I finally got it today.  The key turned out to be creating a SIP hard phone and playing with that until I got it right, then doing the same with CUCILync.

Anyway, the salient parts of the running configuration are at the bottom of this post.  There is a standard SRST portion at the bottom of the config. ("call-manager-fallback") because we have SCCP phones.  I don't know if it's needed or not in an environment with only SIP phones.  I haven't tested it yet because there's a ton of other stuff to do at the moment.

The following is also a link to a page that talks about how to tweak this configuration.

By the way, the SRST configuration on CUCM itself was the same as usual with the exception of the inclusion of an IP for the gateway in the “SIP Network/IP Address” line.  What I found to be interesting was that the CUCILync phone seems to register on UDP port 2000.  At least that’s what it says in the Notification window.

So the configuration to get the phone registered to the gateway is working, but there’s a downside; as soon as CUCILync attaches to SRST for the first time it throws up the “Yield Sign” that lets you know there’s a problem.  It shows that the phone on the computer is down and that SRST is working.  This may not be so bad, but when CUCM comes back up, it still shows the yield sign because now the phone on the computer is working, but the SRST phone isn’t.  What I’ve seen is that after the SRST device is configured you have to make sure that users log out of CUCILync completely.  Then when they log back in they make the connection to CUCM and start to send a keepalive to the SRST router every 2 minutes.  So even though SRST is listed as “Stopped” it’s still maintaining a connection and the warning doesn't get posted.


boot system flash0:c2900-universalk9-mz.SPA.151-4.M3.bin

!Check the IOS, on my system with CUCM 8 I needed IOS 15.1(4)M or better




voice service voip

ip address trusted list


srtp fallback

allow-connections h323 to h323

allow-connections h323 to sip

allow-connections sip to h323

allow-connections sip to sip

fax protocol t38 version 0 ls-redundancy 0 hs-redundancy 0 fallback none


  bind control source-interface GigabitEthernet0/0

  bind media source-interface GigabitEthernet0/0

  registrar server



voice register global

system message SIP SRST

!The above message doesn't show in CUCILYNC, in fact no message shows.

max-dn 300

max-pool 58


voice register pool  1

id network mask

!The above has to be a summary of all of the addresses held by CUCILYNC phones

codec g711ulaw




max-conferences 12 gain -6

transfer-system full-consult

ip source-address port 2000

max-ephones 58

max-dn 200

system message primary Some Capabilities Disabled

time-zone 12 boot-start-marker
boot system flash0:c2900-universalk9-mz.SPA.151-4.M3.bin

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